Protease sensitive conductive polymer composition and uses thereof

Abstract

An electrically conductive composition is provided, comprising a dialcohol cellulose, an electrically active material comprising an electrically conducting polymer and a protease digestible protein.

Description

[0001] PROTEASE SENSITIVE CONDUCTIVE POLYMER COMPOSITION AND USES THEREOF

[0002] Technical Field

[0003] The present disclosure relates to an electrically conductive composition comprising a dialcohol cellulose, an electrically active material comprising an electrically conducting polymer, and a protease digestible protein. The present disclosure also relates to a substrate comprising a conductor arrangement, at least partly formed from such composition an electrically conductive composition deposited on a material layer, an absorbent hygiene article comprising such a substrate, and the use of such an electrically conductive composition in a sensor to detect the presence of proteases.

[0004] Electrically conductive compositions comprising a dialcohol cellulose and an electrically active material comprising an electrically conducting polymer, as well as various uses of such compositions are known from SE 2250677.

[0005] Such electrically conductive composition can be made to form electrical circuits on different materials, such as textiles, non-woven materials and films.

[0006] Wearable absorbent articles, such as e.g., wound dressings or diapers, comprising at least one material layer and a conductor arrangement that is at least partially deposited on, optionally printed onto, the material layer wherein the conductor arrangement is formed from a composition comprising a dialcohol cellulose and an electrically conductive material, are known from WO 2023 / 232263.

[0007] The conductor arrangements in WO 2023 / 232263 are essentially passive since the composition and its intrinsic electrical properties are relatively stable. However, there is a need in the art for electrically conductive compositions that are active in the sense that their intrinsic electrical properties change in response to being exposed to certain material.

[0008] The object of the present invention is to at least partly meet the need in the art and to provide an electrically conductive composition whose intrinsic electrical properties change in response to being exposed to proteases.

[0009] This is met by an electrically conductive composition as defined in claim 1, comprising a dialcohol cellulose, an electrically active material comprising an electrically conducting polymer, and a protease digestible protein. Due to the presence of the protease digestible protein in the electrically conductive composition, it is sensitive to proteases that can digest the protease digestible protein. Upon such digestion, intrinsic electrical properties of the electrically conductive composition have been shown to change, and the electrically conductive composition can therefore be useful, inter alia as or in a sensor to detect the presence of proteases in a sample.

[0010] The electrically conducting polymer may consist of or comprise PEDOT:PSS. PEDOT:PSS has shown to exhibit excellent compatibility with dialcohol cellulose as well as good electrical properties.

[0011] The protease digestible protein may be a trypsin digestible protein. Trypsin is abundantly present in e.g. feces, and therefore the composition may be used in a sensor for detecting feces. Examples of protease digestible proteins include serum albumins, for example Bovine Serum Albumin, transferrins and transthyrethins

[0012] The electrically conducting composition may further comprise a plasticizer, such as glycerol and / or DMSO.

[0013] The electrically conducting composition may further comprise a cross-linking agent, such as selected from the group consisting of ionic cross-linkers, photo cross-linkers and covalent cross-linkers and combinations thereof.

[0014] The electrically conducting composition may comprise from 10 to 95 wt% of dialcohol cellulose, based on the dry weight of the composition.

[0015] The electrically conducting composition may comprise from from 5 to 70 wt% of electrically conducting polymer, based on the dry weight of the composition.

[0016] The electrically conducting composition may comprise from 1 to 80 wt%, of protease digestible protein, based on the dry weight of the composition.

[0017] The electrically conducting composition may comprise from 0.5 to 50 wt% of plasticizer based on the dry weight of the composition.

[0018] In the electrically conducting composition the dialcohol cellulose may comprise fibers having an average diameter of at least 1 pm, such as at least 5 pm, such as at least 8 pm, such as at least 12 pm.

[0019] The electrically conducting composition may be deposited on the surface of a substrate, for example a polymer film, textile, non-woven or paper substrate. In another aspect, the present disclosure relates to a substrate comprising a conductor arrangement, at least partly formed from a composition of the present disclosure, deposited on at least one surface of said substrate.

[0020] The conductor arrangement may be connected or connectible to a measuring device adapted to measure at least one electrical property of the conductor arrangement.

[0021] The measuring device may be adapted to detect changes in said at least one electrical property, such as a resistance or impedance.

[0022] The substrate may be comprised in a wearable absorbent article, such as a wound dressing or a hygiene absorbent article, e.g. a diaper.

[0023] In another aspect, the present disclosure relates to an absorbent article, for example an absorbent hygiene article, comprising a substrate of the present disclosure.

[0024] In another aspect, the present disclosure relates to the use of a composition of the present disclosure in a sensor to detect presence of protease containing matter. The protease containing matter may be feces.

[0025] These and other aspects of the present disclosure will now be described further with reference to the enclosed drawings.

[0026] Drawings

[0027] Figure 1 is a picture of the test electrode used in the experiment.

[0028] Figure 2 is a picture of the test electrode with an electrically conductive composition deposited on it.

[0029] Figure 3 is an impedance spectrum of a reference experiment using a reference composition without any protease digestible protein in the electrically conductive composition.

[0030] Figure 4 is an impedance spectrum of an experiment using a composition with Bovine Serum Albumin in the electrically conductive composition.

[0031] Detailed Description

[0032] In one aspect, the present disclosure relates to an electrically conductive composition comprising a dialcohol cellulose, an electrically active material comprising a conductive polymer and a protease digestible protein.

[0033] The dialcohol cellulose may be in the form of DALC fibers or DALC nanofibrils. DALC fibers and nanofibrils can be prepared using methods known by a person skilled in the art. For example, DALC fibers can be obtained by oxidizing cellulose in a fiber suspension to dialdehyde cellulose followed by reduction of dialdehyde cellulose to obtain the dialcohol cellulose. If desired, DALC nanofibrils can then be obtained by micro-fluidization or mechanical processing of DALC fibers.

[0034] As used herein "Dialcohol cellulose" or "DALC" or "dialcohol modified cellulose fibers" refers to modified cellulose that may be obtainable, for example, by a method comprising oxidizing cellulose in a fiber suspension to dialdehyde cellulose followed by reduction of dialdehyde cellulose to obtain the dialcohol cellulose. Some of the methods to obtain DALC are further discussed in patent application WO2018 / 135994.

[0035] The terms also incorporate DALC nanofibrils, cellulose-based nanofibrils obtainable by microfluidization or mechanical processing of DALC fibers. It is to be understood that while both cellulose nanofibrils and fibers that have been dialcohol modified can be referred to as dialcohol cellulose, nanofibrils have a diameter of a few nanometers, such as less than 1000 nm, preferably less than 500 nm, or less than 200 nm, or less than 100 nm, or 50 nm, while fibers are in the micrometer range, may have but not limited to a diameter of at least 1 pm, such as at least 5 pm, such as at least 8 pm, such as at least 12 pm. The length of the fibers and nanofibrils may be in a micrometer or a millimeter range.

[0036] The cellulose source for the DALC may be any, optionally modified, cellulose. For example, Carboxymethyl cellulose (CMC) and Microfibril Cellulose (MFC) are suitable cellulose sources.

[0037] In general, when referring to DALC it is understood that a certain amount of the cellulose has been modified. Typically, the modification desired depends on the application. However, generally for the applications disclosed herein a degree of modification or degree of substitution 10% to 50% is sufficient. However, lower or even higher degrees of substitution or modification may also be used.

[0038] The electrically conductive composition of the present disclosure may comprise from 10, 30 or 40 to 95, 85 or 75 wt% of the dialcohol cellulose, based on the dry weight of the composition, such as 10-95, 30-85 or 40-75 wt%.

[0039] The electrically active material in the electrically conductive composition of the present disclosure refers to any material that transmits a current, for example, an electrically conductive material. The electrically active material comprises or consists of an electrically conductive polymer. It is understood that by the term 'electrically conducting polymer' is also meant a mixture or a complex comprising several polymers, which may be with or without electrically conducting properties on their own, provided that the mixture exhibits electrically conducting property.

[0040] The electrically conductive polymer may, for example, comprise one or more polymers selected from the group consisting of polyphenylenes, polypyrenes, polyazulenes, polynaphthalenes, polyacetylenes (PAC), poly-p-phenylene vinylene (PPV), polypyrroles (PPY), polyazepines, polyanilines (PANI), polythiophenes (PT), poly-3, 4-ethylenedioxythiophene (PEDOT), toluenesulfonyl (Tos) and a polystyrene sulfonates (PSS). PEDOT:PSS is especially suitable for use as the electrically conductive polymer in the conductive composition of the present invention.

[0041] As used herein "PEDOT:PSS" refers to a polymeric compound, also called a polymer complex, comprising poly-3, 4-ethylenedioxythiophene (PEDOT) and polystyrene sulfonate (PSS) in any ratio. PEDOT:PSS is readily available from multiple suppliers. The weight ratio between PEDOT and PSS in commercially available PEDOT:PSS is commonly 1:2.5. However, it is generally understood that changing the ratio in what is commonly available doesn't affect the use in any considerable way.

[0042] The electrically conductive composition of the present disclosure may comprise from 5, 10 or 20 to 70, 50 or 40 wt% of the electrically conductive polymer material, based on the dry weight of the composition to such as from 5 to 70 wt%, from 10 to 50 wt% or from 20 to 40 wt%.

[0043] The electrically conductive composition of the present disclosure comprises a protease digestible protein.

[0044] It was shown by the inventors that the intrinsic electrical properties of the conductive composition changes with digestion of the protein by means of a protease. This led to the insight that the electrically conductive composition of the present disclosure can be useful in applications of detecting the presence of proteases in different matter.

[0045] The protease digestible protein may be a protein that is digestible by trypsin. Trypsin is an enzyme found in the first section of the small intestine. Its primary role is to start the digestion of protein molecules by cutting long chains of amino acids into smaller pieces. As a serine protease, it hydrolyzes proteins and is essential for protein absorption in the small intestine. Trypsin is produced as an inactive form called trypsinogen in the pancreas and is activated in the duodenum. Once activated, it catalyzes the hydrolysis of peptide bonds, breaking down proteins into smaller peptides, which are then further hydrolyzed into amino acids for absorption into the bloodstream.

[0046] It is noted that trypsin is abundantly present e.g. in feces, and therefore the electrically conductive composition of the present disclosure may be used in a sensor to detect feces, to be further elaborated on herein.

[0047] Examples of trypsin digestible proteins suitable for inclusion in the electrically conductive composition of the present invention includes, but are not limited to albumins, such as serum albumins, for example bovine serum albumin, transferrins and transthyrethins. The electrically conductive composition of the present disclosure may comprise from 1, 2 or 3 to 80, 50 or 10 wt% of the protease digestible protein, based on the dry weight of the composition, such as from 1 to 80, from 2 to 50, or from 3 to 10 wt%.

[0048] The electrically conductive composition of the present disclosure may comprise a plasticizer.

[0049] As used herein, the term "plasticizer" commonly refers to a substance or material incorporated in the matrix forming material to increase its flexibility or workability. Many plasticizers tend to decrease the intermolecular forces between polymer chains, resulting in the increased flexibility and compressibility, or they may exert a plasticizing effect since they cause discontinuities in a polymer matrix. Examples of classes of plasticizers are saccharides (mono-, di- or oligosaccharides), alcohols, polyols, acid, salts, lipids and derivatives (such as fatty acids, monoglycerides, esters, phospholipids) and surfactants. Specific examples of suitable plasticizers include but are not limited to glucose, fructose, sorbitol, erythritol, polyethylene glycol, glycerol, propylene glycol, lactitol, sodium lactate, hydrated hydrolyzed starches, trehalose, or combinations thereof such as honey. Other suitable plasticizers for use in the present disclosure include DMSO and ionic liquids.

[0050] Without being bound by theory, glycerol as the plasticizer, when combined with DALC and PEDOT:PSS, may enhance the separation of PEDOT and PSS, thus increasing the conductivity of the composition. The addition of glycerol also may enable the composition to retain a gel nature of the composition, with increased wet stability and adhesion to substrates. Wet stability and the ability of the composition to retain moisture can prolong the shelf life of devices based on the composition of the present disclosure.

[0051] The electrically conductive composition of the present disclosure may comprise from 0.5 or 1 to 50 or 25 wt% of the plasticizer, based on the dry weight of the composition, such as from 0.5 to 50 or from 1 to 25 wt%. The suitable amount of plasticizer will eventually depend on what plasticizer compound is used.

[0052] The electrically conductive composition of the present disclosure may comprise a cross-linking agent.

[0053] As used herein, the terms "cross-linking agent" or "cross-linker" refers to chemical entities capable of forming cross-linking chains between polymers; as well as agents capable of providing cross-linking of polymer chains in the presence of the appropriate reagents, such as gamma-irradiation, or other types of electromagnetic radiation, or electron bombardment.

[0054] The electric conductivity of the electrically conductive composition of the present disclosure may vary for different applications. E.g. for wearable devices an electric conductivity of around 0.1 S / cm is commonly used, but for e.g. electronic paper an electric conductivity of 100, or even 150, S / cm may be desired. Thus, the composition may have an electric conductivity from 0.05 S / cm to 150 S / cm, such as from 0.1 S / cm to 100 S / cm, such as from 1 to 100 S / cm.

[0055] The electric conductivity relates to that of the electrically conductive composition before having been exposed to a protease, i.e. with the protein of the composition being un-digested.

[0056] Methods for preparing an electrically conductive composition comprising a dialcohol cellulose and an electrically active material comprising an electrically conducting polymer are disclosed in SE 2250677.

[0057] In short, a cellulosic material is oxidized, for example with Sodium Iodate. This oxidation breaks C2-C3 carbon-carbon bonds in the cellulose to form two aldehyde groups. The aldehyde groups are subsequently reduced for example with Sodium Borohydride to alcohol group. The resulting dialcohol cellulose (DALC) exhibits unique properties due to its open-ring structure, making it flexible and distinct from regular cellulose with a closed ring structure.

[0058] DALC , obtained according to this or other methods, is then mixed with an electrically active agent comprising an electrically conductive polymer, such as for example PEDOT:PSS.

[0059] Plasticizers and cross-linking agents may also be introduced into the mixture.

[0060] The electrically conductive composition of the present disclosure may be obtained by also introducing the protease digestible protein into this composition, for example as an aqueous composition comprising the protein.

[0061] The electrically conductive composition of the present disclosure can be further processed into an electrically conductive material deposited on the surface of a substrate. Examples of processing techniques include but not limited to extruding, printing or solution processing techniques, such as 3D- printing, 2D-printing, screen printing, stencil printing, blade-coating, melt-processing, molding, slot die coating, inkjet printing, laser printing, solution processing, vacuum filtration, solvent casting and / or paper making techniques.

[0062] Suitable substrates on which the electrically conductive composition of the present disclosure can be coated is not specifically limited, however, it has been shown that the composition is rather flexible, i.e. it can be bended and stretched to a certain degree without breaking, and it is therefore suitable to for flexible substrates, such as films, textiles, nonwovens, paper, etc. However, the substrate may also be a more rigid substrate, e.g. such materials commonly used for printed circuit boards.

[0063] In some embodiments, the composition is at least partly dried before, during and / or after applying the composition. In some embodiments, the composition is at least partly cured before, during and / or after applying the composition.

[0064] The electrically conductive composition of the present disclosure may, when deposited on a surface of a substrate form part of a conductor arrangement, i.e. it may be part on an electric circuit. Especially, such conductor arrangement may be connected to, or connectible to, a measuring device adapted to measure at least one electrical property of the conductor arrangement, in particular where the measuring device is adapted to detect changes in said at least one electrical property. The electrical property which the measuring device can measure may for example be a resistance or impedance of the conductor arrangement.

[0065] The substrate with such conductor arrangement may be an integral part of or may be adapted to be inserted into a wearable article, such as clothing, a wound dressing or an absorbent hygiene article, for example a diaper or incontinence protection.

[0066] Due to the sensitivity of the electrically conductive composition to proteases, the electrically conductive composition, for example when forming part of a conductor arrangement as described herein, may be useful in a sensor to detect the presence of such proteases in matter brought into contact with the electrically conductive composition. One such protease is trypsin, which is abundantly present in e.g. feces, and the sensor may therefore be a sensor to detect feces. For example, such a sensor may be integral or intended to be placed into an absorbent hygiene article, such as a diaper or incontinence protection. Upon contact with feces, e.g. after a voiding event, the trypsin in the feces may start digesting the protein in the electrically conductive composition, thereby changing the intrinsic electrical properties of the composition. By monitoring the electrical properties and detecting a change using a measurement device, the change can be noted and an appropriate signal can be sent, inter alia to a caregiver, for example via a wireless connection.

[0067] Experiments

[0068] Preparation of Electrically Conductive Composition

[0069] The electrically conducting composition was made in the form of a gel. The gel is highly favorable to be used as sensing material because leakage of components is zero during the interaction and sensing of enzyme.

[0070] Functionalization of Cellulose

[0071] One liter of Milli-Q. water, equal to one kilogram of water at room temperature, was mixed with 6.3 Volume % or 4.95 g of > 98 % isopropanol (Sigma Aldrich). Into this mixture 4 grams of microfibril cellulose (MFC) was added under constant stirring. After that 21.6 gram of 99.9% pure sodium periodate (Sigma Aldrich) was added. The mixture was stirred 24 hours in dark by covering the beaker with aluminum foil. The mixture was filtered by using the Whatman filter paper grade 1 of diameter 90 mm. The filtration was done by vacuum pump. The filtered fibers were transferred to 1 liter M ill i-Q water and 1.2 gram of monobasic sodium phosphate was added which is equivalent to 0.01M concentration. Two grams of sodium borohydride was added to the mixture and it was stirred for four hours. The mixture was filtered as described above and cellulose were dried at room temperature. The functionalization of cellulose fibers was determined by analyzing with Fourier Transform Infra Red (FT-IR) spectroscopy.

[0072] Addition of Electrically Conductive Polymer

[0073] One gram of functionalized cellulose was added in 15 mL Milli-Q water under gentle stirring to get homogeneous mixture. To this mixture 0.25 grams of PEDOTS:PSS was added under constant stirring. The mixture was stirred maximum 5 minutes. Note that the PEDOTS:PSS used in this study had pH 7.

[0074] Addition of glycerol

[0075] A 5 volume % solution of glycerol was prepared by diluting the appropriate amount of 90% glycerol stock solution in Mil l-Q. water. A 0.25 gram of 5% glycerol solution was weighed and added to the above mixture under stirring.

[0076] Addition of Protein

[0077] 0.05 gram of bovine serum albumin (BSA) which > 99 % pure purchased from Sigma Aldrich, was added to 4.95 gram Milli-Q water. This makes total weight of the solution 5 gram.

[0078] 1.75 ml (added in portions of 0.25 ml using a pipette) of the BSA solution was added to the mixture containing cellulose, PEDOTS:PSS and glycerol as described above.

[0079] This resulted in an electrically composition containing about 77 wt% DALC, about 20 wt% PEDOT:PSS, about 1 wt% Glycerol and about 2 wt% BSA, based on the dry weight of the composition.

[0080] The aqueous composition was transferred to cubic plastic container and was dried at the room temperature in fume hood for two hours, resulting in a gel-like composition. This gel then applied onto electrodes for impedance measurements as will be detailed below.

[0081] Investigation of electrical properties

[0082] Impedance properties of the electrically conductive properties and the response to exposure of trypsin was tested. A CTI Phase Zero SPE electrode as depicted in Figure 1, obtained from company Palmsens BV, NL, was used in the experiment and the electrical properties of the electrode was read using a Palmsens4 device, run in the impedance mode. An amplitude of 10 mV was used to perturb the system and frequency range used for measurements was 5 to 50,000 Hertz (Hz).

[0083] The electrochemical response of sensor was measured by Impedance spectroscopy. A three-electrode system which consist of working electrode, counter electrode and a reference electrode was used.

[0084] The electrically conductive composition, the gel produced as described above, consisting of DALC, PEDOT:PSS, glycerol and BSA was deposited on the electrode covering all three electrodes as shown in figure 2.

[0085] In a reference example, the gel produced as described above, but without addition of BSA, was used.

[0086] A trypsin solution was added on top of the conductive composition (3.5 pl of a 0.25 wt% solution in PBS buffer, Sigma Aldrich) and impedance measurements were performed after certain time had lapsed since addition, as indicated in the figures.

[0087] As can be seen from figure 3, addition of trypsin to the reference composition, i.e. without any protein, did not result in any change in the impedance signal after 0, 10, 20 or 30 minutes.

[0088] As can be seen from figure 4, addition of trypsin to the composition of the present disclosure resulted in a change in impedance signal already within 5 minutes after addition, with an increasing change in the signal with the elapsed time (10, 20, 30, 40 and 50 minutes).

[0089] The results show that the intrinsic electrical properties of the electrically conductive composition changes in a detectable manner upon exposure to a protease.

Claims

CLAIMS1. An electrically conductive composition, comprising;(a) a dialcohol cellulose;(b) an electrically active material comprising an electrically conducting polymer; and(c) a protease digestible protein.

2. The composition of claim 1, wherein the electrically conducting polymer consists of or comprises PEDOT:PSS.

3. The composition of claim 1 or 2, wherein the protease digestible protein is a trypsin digestible protein.

4. The composition according to any of the preceding claims, therein the protease digestible protein is selected from the group of serum albumins, for example Bovine Serum Albumin, transferrins and transthyrethins5. The composition according to anyone of the preceding claims, further comprising a plasticizer.

6. The composition according to claim 5, wherein the plasticizer comprises at least one of glycerol and DMSO.

7. The composition according to anyone of the preceding claims, further comprising a crosslinking agent, preferably selected from the group consisting of ionic cross-linkers, photo crosslinkers and covalent cross-linkers.

8. The composition according to anyone of the preceding clams, comprising from 10 to 95 wt% of dialcohol cellulose, based on the dry weight of the composition.

9. The composition according to anyone of the preceding claims, comprising from 5 to 70 wt%, such as 20 to 60 wt% of electrically conducting polymer, based on the dry weight of the composition.

10. The composition according to anyone of the preceding claims, comprising from 1 to 80 wt%, of protease digestible protein, based on the dry weight of the composition.

11. The composition according to anyone of the preceding claims, comprising from 0.5 to 50 wt% of plasticizer based on the dry weight of the composition.

12. The composition according to anyone of the preceding claims, wherein the wherein the dialcohol cellulose comprises fibers having an average diameter of at least 1 pm, such as at least 5 pm, such as at least 8 pm, such as at least 12 pm.

13. The composition according to anyone of the preceding claims, deposited on the surface of a substrate, for example a polymer film, textile, non-woven or paper substrate.

14. A substrate comprising a conductor arrangement, at least partly formed from a composition according to any one of the preceding claims, deposited on at least one surface of said substrate.

15. The substrate according to claim 14, wherein said conductor arrangement is connected or connectible to a measuring device adapted to measure at least one electrical property of the conductor arrangement.

16. The substrate according to claim 15, there the measuring device is adapted to detect changes in said at least one electrical property.

17. The substrate according to claim 16, wherein the electrical property is a resistance or impedance.

18. The substrate according to any one of claims 14 to 17, comprised in a wearable absorbent article, such as a wound dressing or a hygiene absorbent article, e.g. a diaper.

19. An absorbent article, for example an absorbent hygiene article, comprising a substrate as defined in any of the claims 14 to 18.

20. The use of a composition as defined in any one of the claims 1-13 in a sensor to detect presence of protease containing matter.

21. The use according to claim 20, wherein said protease containing matter is feces.

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